**Thyroid supplements are tricky—what helps some people can harm others.** Selenium has the best evidence, particularly for autoimmune thyroid conditions. Iodine is essential but dangerous if you have Hashimoto's or take too much. Get tested before supplementing.
Generally Helpful
Selenium is required for the enzymes that convert T4 to active T3. Multiple studies show selenium reduces thyroid antibodies in Hashimoto's. The thyroid contains more selenium per gram than any other organ.
Zinc is required for thyroid hormone synthesis and T4 to T3 conversion. Deficiency impairs thyroid function. Studies show zinc supplementation improves T3 levels in deficient individuals.
Use With Caution
Iodine is the raw material for thyroid hormones. True deficiency causes hypothyroidism. However, excess iodine can trigger or worsen Hashimoto's, cause hyperthyroidism, or paradoxically cause hypothyroidism.
Some studies show ashwagandha increases T4 and T3 levels in subclinical hypothyroidism. It may help normalize thyroid function. However, it can cause hyperthyroidism in some people, so monitoring is essential.
Thyroid Support Stack
Supportive nutrients for thyroid health (get tested first).
| Ingredient | Dose | When |
|---|---|---|
| Selenium | 100-200mcg | With food |
| Zinc | 15-30mg | With food |
| Vitamin D | 2,000-5,000 IU | Morning (low D is common in thyroid disorders) |
Beyond Supplements
- •Get a full thyroid panel (TSH, Free T4, Free T3, TPO antibodies, Thyroglobulin antibodies)
- •Gluten may worsen Hashimoto's in some people—consider elimination trial
- •Stress management matters—chronic stress impairs T4 to T3 conversion
- •Goitrogens (raw cruciferous) are fine in normal amounts
Note: Thyroid disorders require medical diagnosis and management. These supplements support but don't replace thyroid medication. Iodine can worsen autoimmune thyroid disease. Test before supplementing.